It may be desirable to provide passive beam forming networks for complex beam forming using antenna arrays such as those shown and described in the above referenced patent applications entitled “Co-Located Antenna Array for Passive Beam Forming.” For example, for different environments it may be desirable to provide different radiation patterns to effectively optimize performance of a communication system.
A passive beam forming network effects a radiation pattern using an antenna array having a particular geometry, wherein the antenna array comprises individual arrays or individual antennas which are slaved together. Accordingly, a beam forming network may be designed which, when utilized with an antenna array having a particular geometry, results in a desired radiation pattern. In operation, a passive beam forming network distributes signal energy to/from the individual elements in an antenna array.
For example, a passive beam forming network distributes the energy to each of the elements in the array such that each element is driven with a certain amplitude and phase in relation to other ones of the elements in the array. Such amplitudes and phases comprise what are often referred to as “weights”, wherein a set of weights (amplitude and phase values) may be associated with a given radiation pattern. An individual weight is associated with an individual antenna element or element array, e.g., an antenna element column, in the antenna array. A particular set of weights to provide a desired radiation pattern is dependent on the specific antenna structure utilized. Accordingly, once a desired radiation pattern is known, that uniquely determines a set of weights that may be utilized in providing the radiation pattern using a particular antenna configuration.
In the past, designing complex beam forming networks has required the talents of a skilled radio frequency (RF) engineer and, typically, many hours of design time. For example, implementing a particular desired radiation pattern typically would require an RF engineer to design a beam forming network using his background and experience in designing these networks as well as computer aided drafting (CAD) tools and the like to layout the components of a feed network using trial and error and some level of intuition. For example, the RF engineer may first determine how to divide the signal power in the beam forming network to arrive at the desired amplitudes of the weight set. Thereafter, the RF engineer may work to derive a component layout, such as on a printed circuit board (PCB) using, for example, microstrip or stripline technology.
Accordingly, once an RF engineer is given a desired radiation pattern's requirements, i.e., the weights that are to be incorporated into a beam forming network, the engineer might go through a process of deciding the structure and the layout of the beam forming network. This could be a lengthy process, on the order of a few days. If it were desired to generate many beam forming networks, such a process would require many RF engineers and/or considerable lead time. Such an approach, in addition to being an expensive proposition, does not readily facilitate the manufacture of a large number of such passive beam forming networks, such as for providing unique radiation patterns throughout a communication network and/or to provide reconfigured beam forming networks in response to topology and morphology changes in the network.
A need therefore exists in the art for a beam forming network design approach which is less dependent upon the skills of an individual, such as an RF engineer.